Global Mapper Pro Coming Soon

Curiousity making DTED with GM

dmrdmr Global Mapper UserPosts: 23Trusted User
edited October 2011 in Elevation Data
I made DTED from NED (adf) with GlobalMapper. When I batch exported DTED1, it was perfect (27 files in, 27 files out). Then from the same NED, I did a second batch export of DTED2. For some reason it made 3 adjacent tiles for every output tile. So instead of the expected 27 files, I got 108. They are all a full geocell, not like they got quaded up or anything. And they all look legit. Just a lot of extra processing and redundant files. For example, it made these 4 files for one input:
1) w001001_W120_N34.dt2
2) w001001_W120_N35.dt2 ---> the correct output
3) w001001_W121_N34.dt2
4) w001001_W121_N35.dt2

Settings I used:
File > Batch Convert/Reproject...
convert from = Arc/Info Binary Grid
convert to = DTED
Add Loaded Files button (27 total .adf files)
Use same directory as being converted
use source file name
use source projection
Horiz Datum = Source Datum
Level = DTED2
Use other Source files as filler
Force square pixels
Fill small gaps in data

I am on GM 10.02.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Can you post one of your source tiles that generates the extras? I'm guessing that your source NED data extends slightly beyond the bounds of the central DTED2 tile boundary into the adjacent DTED2 tile boundaries, so the additional outside tiles are generated as well, although they would be pulling almost entirely from the other loaded source files.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • dmrdmr Global Mapper User Posts: 23Trusted User
    edited March 2010
    The NED files are equivalent to 10m post spacing. So one file is 500MB. With best .rar compression still about 167MB. Do you really want it?

    Next best thing is I copied the GM metadata from the source NED file I gave you in my example:
    FILENAME=.........\NED\dem12036\w001001.adf
    DESCRIPTION=dem12036 GRID (w001001.adf)
    UPPER LEFT X=-120.0005092593
    UPPER LEFT Y=36.0005092593
    LOWER RIGHT X=-118.9994907407
    LOWER RIGHT Y=34.9994907407
    WEST LONGITUDE=120.00050926° W
    NORTH LATITUDE=36.00050926° N
    EAST LONGITUDE=118.99949074° W
    SOUTH LATITUDE=34.99949074° N
    PROJ_DESC=Geographic (Latitude/Longitude) / NAD83 / arc degrees
    PROJ_DATUM=NAD83
    PROJ_UNITS=arc degrees
    EPSG_CODE=4269
    COVERED AREA=10097 sq km
    NUM COLUMNS=10812
    NUM ROWS=10812
    PIXEL WIDTH=0.0000926 arc degrees
    PIXEL HEIGHT=0.0000926 arc degrees
    MIN ELEVATION=55.676 meters
    MAX ELEVATION=1557.647 meters
    ELEVATION UNITS=meters
    BIT_DEPTH=24

    It validates what you said in that it is a little bit bigger than a geocell. Next step? Do you still want the file even though it is that big?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Thanks, the metadata shows that there is a small overlap of a couple of samples into the adjacent cells, which is causing them to be generated. I may be able to tweak the DTED export to ignore very small overlaps like that though. If you want to FTP the file to ftp.globalmapper.com using a username of 'upload' and a password of 'upload' I can see what I can do.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • dmrdmr Global Mapper User Posts: 23Trusted User
    edited March 2010
    I have uploaded a file named dem12036.rar that is the piece of NED we have been discussing.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Thanks for the file, the problem was indeed that the boundary just barely leaked past what Global Mapper considered a "sliver", so the adjacent tiles were being created. I have very slightly increased what is considered a "sliver" and now you just get one tile. I have placed a new build at http://www.globalmapper.com/global_mapper10.zip with the change for you to try. Simply download that file and extract the contents into your existing v10.xx installation folder to give it a try.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • jeb76jeb76 Global Mapper User Posts: 6
    edited October 2011
    Mike, i am having a similar issue with GM ver 12.2 while running or not running my script file with the slivers while converting the *.adf ned files. I have 1177 files that i need to convert. The empty file generally overwrites the good data file.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited October 2011
    Rather than exporting them individually I would load them all up at once, then export to DTED from there so you get the combined results, otherwise you will have to get the sliver files since DTED defines everything as 1 degree tiles.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • dmrdmr Global Mapper User Posts: 23Trusted User
    edited October 2011
    Hmmmm....Mike - in a similar thread I sent in last month called "Exporting Hawaii NED as DTED", I had been loading up all the data first and then exporting it out. Your suggestion was to run the File->Batch Convert/Reproject instead to avoid empty files.
    Now for jeb76, it sounds like you are saying to do the opposite.
    Am I confused on this? Might need more discussion.

    David
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited October 2011
    David,

    His problem isn't empty tiles though I don't think, it's that his files don't like up with the 1x1 degree DTED boundaries like yours do, so the export for one will overwrite another one that also is in that cell. He could also use File->Batch Convert/Reproject with the 'Use Other Source Files as Filler' option checked, that would actually work for both of you.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
Sign In or Register to comment.